As an information output apparatus for, for example, word processors, personal computers, facsimile machines and the like, printers are widely used to print desired text and image information onto a sheet-like printing medium such as paper or film.
As a printer use embodiment, it is common for printing to be executed by connecting the printer to a host device such as a personal computer, processing the image and text data to be printed into a suitable embodiment for printing at the printer by a printer driver installed in the host device, and transmitting the data to the printer together with control data.
Recently, with the rapid rise in popularity of the digital camera, embodiments thereof have come to range from types that can accommodate interchangeable lenses from single lens reflex, silver halide (i.e., traditional film) cameras to compact, lightweight models that place a premium on portability.
With the spread of digital input devices such as the digital camera, so-called direct printers, which have an interface for a storage medium that stores image data of an external device such as a digital camera or of a memory card and the like, and which execute printing by directly scanning an image from the external device without going through the host device, have attracted notice.
In a printing apparatus of the type described above, ordinarily, a standard is adopted in which the device is configured so that it is possible to supply power via a connection cable such as a USB that is the interface with the external device, with the power necessary to operate that device being supplied when it is detected that an external device is connected.
Accordingly, if a plurality of external devices is connected simultaneously to such a printing apparatus, it is therefore necessary to supply power to those devices simultaneously as well. As a result, the power circuit for this type of printing apparatus must be a large-capacity power unit, capable of reliably supplying power for consumption not only to the printing apparatus itself but also power for consumption to the connectible external devices, resulting in large power costs for such apparatus.
Moreover, in order to increase power unit capacity the power unit itself becomes larger, thus increasing the size of the apparatus as a whole, which is undesirable.